A US woman who shot and killed her husband and two adult children before taking her own life is thought to have committed the shocking crime as a result of being ostracised from the religion she was raised in.

A federal judge sentenced a former Arkansas judge Wednesday to five years in prison — a stiffer punishment than prosecutors recommended — after he admitted giving young male defendants lighter sentences in return for personal benefits that included sexual favours.

Every time I tell a mate I’m doing a story on cryptocurrency, they invariably ask me the same two questions: should they invest their own hard-earned money, and which cryptocurrency will get them a Lamborghini/yacht/island quickest?

In a 60 Minutes online exclusive, reporter Liz Hayes quizzed Australian Prime Minister Malcolm Turnbull on his relationship with the unpredictable Twitter aficionado and US president Donald Trump ahead of their meeting at the White House Friday.

NSW govt issues warning on wheat bags

As the mercury drops and people seek ways to warm their beds, the NSW government is warning that wheat bags can become fire hazards if heated for too long.

Consumer group CHOICE say the cheap and reusable winter warmers "pose a potentially deadly threat" after only a few minutes in the microwave.

"If heated longer than recommended and placed under bed covers or wrapped in a towel, the wheat may smoulder and self-combust, setting fire to the bag and surroundings," CHOICE spokesman Tom Godfrey said in a statement on Thursday.

Two tests were run by CHOICE to determine their danger.

A "typical" wheat bag was microwaved for two minutes at full power for the first assessment.

"The outer material was a comfortably warm 50-55C, but the internal temperature reached well over 70C," Mr Godfrey said.

For the second test, CHOICE used a wheat bag stuffed into a plush toy, which is against instructions, and heated it for longer than recommended.